This invention relates to an apparatus and method for dispensing solid particles.
Many processes require the controlled dispensing of solid particles, i.e. fine grained particulate solids or powders. For example, in sample/reagent preparation, sample materials in particulate or powder form are typically dispensed in a controlled fashion to a vial or other container for weighing or subsequent processing. Commercially available dispensers suitable for such a purpose typically include a hopper and a vibrator for vibrating the hopper at a high frequency so as to move the powder therein through a hopper outlet. One serious limitation of such commercially available dispensing systems is the relatively small capacity, typically around 100 cc, of the hopper. This small hopper capacity requires frequent manual refilling of the hopper where a large amount of solid pariculate is desired to be dispensed continuously, thus resulting in inconvenience and loss of valuable man hours.
It has been found that enlarging the capacity (to for example 500-1000 cc) of the hopper in an attempt to overcome the above described problems caused many fine grain powders to pack in the hopper, particularly at the bottom of the hopper, thus effectively terminating particle flow. Moreover, some packing problems have even been observed employing the small capacity hopper where it is substantially filled with solid material.